There are a variety of circumstances in which it is desirable for a two-wheel trailer to be attachable either to a draw bar at the rear of a towing vehicle or to a fifth wheel or hitch ball which may be in the box of a pickup truck or upon a highway tractor. A draw bar may have a simple pintle connection, or may have a ball on it for a ball and socket connection. A draw bar may be on the rear of a strictly passenger vehicle, or upon the rear of a pickup truck, or upon a farm tractor.
Applicants are aware of only two U.S. patents which disclose a trailer which may be equipped alternately with a gooseneck or a draw bar hitch. Those are U.S. Pat. Nos. 3,698,740 and 3,815,936.